Risk factors for congenital cryptorchidism in a prospective birth cohort study

: Damgaard IN, Jensen TK, Jensen TK, Petersen JH, Skakkebaek NE, Toppari J, Main KM

: 2008

: PloS one

: PLoS One

: 3

: 8

: 1932-6203

DOI: https://doi.org/10.1371/journal.pone.0003051

Risk factors for congenital cryptorchidism were investigated in a prospective birth cohort study in Denmark and Finland from 1997 to 2001.\nIn total, 2,496 boys were examined for cryptorchidism at birth (cryptorchid/healthy: 128/2,368) and three months old (33/2,215). Information on risk factors was obtained antenatally (questionnaire/interview) or at birth from birth records. Use of nicotine substitutes during pregnancy (n = 40) and infertility treatment by intrauterine insemination (n = 49) were associated with an increased risk for cryptorchidism, adjusted odds ratio (95% confidence interval) (OR (95%CI)) 3.04 (95%CI 1.00-9.27) and 3.01 (95%CI 1.27-7.15), respectively. No association was seen for mothers (n = 79) who had infertility treatment in form of intracytoplasmic sperm injection (ICSI) or in vitro fertilization (IVF) treatment (OR 0.71 95%CI 0.21-2.38). In total, 728 (29%) reported to have smoked during pregnancy, however, no increased risk among maternal smokers was found. Furthermore, we found statistically significant associations between cryptorchidism and low birth weight, prematurity, being small for gestational age, substantial vaginal bleeding, and breech presentation, which are in accordance with other studies.\nOur study revealed two novel risk factors for cryptorchidism: intrauterine insemination and the use of nicotine substitutes in pregnancy. This suggests that cryptorchidism may not only be associated to genetic factors, but also to maternal lifestyle and exposure.\nBACKGROUND\nMETHODOLOGY AND PRINCIPAL FINDINGS\nCONCLUSIONS AND SIGNIFICANCE